The present invention relates to flooring systems and more particularly to access floor panels.
In many installations, it is necessary or desirable to include an access floor system which is elevated above the structural floor of a building. The space between the structural floor and the access floor system contains power cables, communication cables, heating, cooling and ventilation equipment, communication equipment and the like. The raised floor system permits easy installation, renovation and interconnection of a wide variety of systems, such as computer equipment and the like.
A typical access floor system includes a plurality of floor panels supported on pedestals. A typical panel is approximately two feet square. The panel is supported at its corners on the pedestals which rest on the structural floor. Bridge channels or stringers are sometimes installed between the pedestals to provide lateral stability and increased strength.
Various forms of floor panels have heretofore been proposed. The panels may be of wood structure or of a high density composite core having galvanized steel sheets laminated to opposite floor surfaces. In this latter form, channels are sometimes welded to the perimeter of the steel sheets. These forms of panels have a high cost-to-strength ratio. Other forms of panels include a cement mixture core and metal cover sheets. These systems suffer from various problems, including difficulty of manufacture, high cost and insufficient strength or stability. Examples of prior systems may be found in U.S. Pat. No. 3,759,009, entitled COMPOSITE LOAD BEARING PANELS and issued on Sept. 18, 1973 to Ransome; U.S. Pat. No. 2,154,036, entitled CONSTRUCTIONAL FINISH DETAIL ELEMENT and issued on Apr. 11, 1939 to Doherty; and U.S. Pat. No. 1,845,711, entitled TILE AND FLOOR WITH SPECIAL METAL WEARING SURFACE and issued on Feb. 16, 1932 to Honig.
Commonly owned U.S. patent application Ser. No. 519,468, entitled ACCESS FLOORING PANEL, filed on Aug. 4, 1983 by Swers et al, now U.S. Pat. No. 4,606,156, discloses a unique panel which solves most of the aforementioned problems. The panel includes a lanced metal pan having tabs oriented generally radially inwardly toward a central portion of the pan. The pan is filled with a lightweight concrete mixture which encapsulates the tabs. The direction of the lances and the construction prevents ripping of the tabs under load. The metal pan provides tensile strength, and the concrete mixture provides compressive strength.
Commonly owned U.S. patent application Ser. No. 743,987, entitled APPARATUS AND METHOD FOR CASTING CONCRETE PANELS, filed June 12, 1985, in the names of Munsey et al, discloses an apparatus including a turntable which rotates about a vertical axis with a mold in a generally horizontal plane. A concrete mixture is poured into the mold and fills a metal pan or other reinforcing member positioned within the mold. The concrete mixture is rotationally cast. Provision is made for vibrating the mold during the casting operation. The rotation of the mold centrifugally casts the panel, resulting in a uniform distribution of the concrete mixture. Secondary manufacturing steps, such as grinding operations, are eliminated.
Heretofore, problems have been experienced obtaining the necessary stability and strength in access floor systems. As mentioned above, stringers or bridge channels have been needed. Such increases the cost and complexity of the system. Also, problems have been experienced with noise caused by contact between the panels and the support pedestals. A need exists for a panel and system which reduces system complexity while achieving the necessary strength and stability.